EP 2 196 232 A1 describes a drive mechanism for a medication delivery device comprising a housing having a proximal end and a distal end, a rotation member which is adapted to be rotated in a first direction with respect to the housing during setting of a dose of a medication and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction, a piston rod, which is adapted to be displaced in a distal direction with respect to the housing for delivering the dose, a drive member, which follows rotational movement of the rotation member in the second direction during delivery of the dose, and a stop member, which prevents rotational movement of the drive member with respect to the housing in the first direction during setting of the dose. The rotational movement of the drive member in the second direction is converted into movement of the piston rod in the distal direction with respect to the housing. The medication delivery device is provided with the drive mechanism and with a cartridge containing the medication. An empty cartridge can be replaced with a new cartridge, so that the medication delivery device is reusable. The replacement of the cartridge requires a reset of the piston rod to an initial position at the proximal end.
The invention relates to a new drive mechanism for a drug delivery device, particularly for a reusable drug delivery device, providing an easy reset of the piston rod. The invention further relates to a new drug delivery device, particularly a reusable drug delivery device, wherein the change of a drug container is facilitated.
This is achieved with a drive mechanism according to claim 1 and with a drug delivery device according to claim 11. Embodiments and variants derive from the dependent claims.